The amount of money Steam charges as a commission isn’t public information, but I’ve been told by multiple sources that most digital distribution platforms take around 30 percent off commission for selling the game. That still gives the developer or publisher the lion’s share of the sale, and the massive amount of publicity that Steam can help give games is certainly worth the price being asked, but if you know you’re going to buy a game, why not give the developer more of your money?
If you see a developer selling a game directly, give some thought to buying it that way, as long as you feel comfortable. Many Humble Store links give you a redeemable Steam key for your purchase anyway. We’re going to make a better effort to link directly to Humble Store links and the official pages of developers to encourage this practice.
Again, buying from Steam, or your favorite platform, is perfectly fine. Supporting games in any way is a good thing. But if you have the option, buy direct from the people making the game. The difference can be substantial, and it helps them make more games in the future, and it’s likely the cost to you is exactly the same. The difference can mean an extra 20 to 25 percent of the cash going directly to those that made the game, and that's a great thing.